the MkIII is physically a big camera for people who are serious about their photography. there are tons of options that didn't exist 7 years ago, mirrorless interchangeable lens cameras, even ones with slightly smaller sensors like the micro four thirds (m43) from Panasonic and Olympus, will get you significantly better image quality than what you're used to in a small package that is easy to carry. m43 cameras have a huge selection of excellent lenses and they're small. small is an advantage: its easy to take with you, and so you'll get more pics from it because carrying a large camera can be a drag.

m43 is hardly the only mirrorless option. There's fuji, sony and others. and lot of folk love Olympus and Fuji jpegs.